In the watchmaking field, a conventional architecture is used to make movements which are fitted with striking mechanisms, such as minute-repeaters. In these embodiments, the gong used is a circular metal wire placed in a parallel plane to the watch dial. The metal wire is arranged around the movement, inside the watch frame. One end of the gong is fixed, for example by a brazing-solder, to a gong-carrier. The other end of the gong is generally free. The gong-carrier is secured to the watch plate and holds the metal wire above the watch plate. The watch includes a hammer which is activated at predetermined times. The gong vibration is produced by the impact of the hammer on the gong of the gong-carrier. The hammer makes a partial rotation in the plane of the gong to make the gong vibrate in its plane. Part of the gong vibration is transmitted to the watch plate. The plate then vibrates in a parallel plane to the plane of the gong.
The vibration obtained comprises several natural frequencies, the number and intensity of which, particularly within the audible field, depend upon the geometry of the gong and the physical properties of the material. Generally, to produce a musical sound of fixed pitch in the entire sound spectrum, there is a fundamental frequency, which is also called the first harmonic, and one or several harmonics, which are integer multiples of the fundamental frequency. In other cases where frequencies higher than the fundamental are not whole multiples of the lowest frequency, they are defined as “partials”. A sound with several partials is found mainly in percussion instruments, or some string instruments, or during strike transients, such as the shock or impact of a hammer against the gong of a watch striking work.
In practice, the ring volume is relatively limited and the energetic yield of the striking work is relatively low. Moreover, the sound quality of the striking work remains generally poor because the transmitted sound has a low number of natural frequencies.
There also exists, in the state of the art, a striking mechanism embodiment, which is formed of a hammer, rotatably mounted about an axis of rotation that is perpendicular to a base plate, for striking a bell fixed to the base plate. U.S. Pat. No. 1,001,095 A and FR Patent No. 2 480 453 A1 can be cited in this regard. The bell fixed to the base plate can also be replaced by a spiral-shaped gong, as disclosed in DE Patent No. 443 387 C. However, none of these embodiments provides a relatively high ring volume and sufficient sound quality.